Method of making commutators



Oct. 19, 1965 w. T. ECHTER METHOD OF MAKING COMMUTATORS Filed Feb. 8. 1961 am, 1 7 w H H w M H 2 li VJ WILL/AM 7. [Cl-I751? INVENTOR.

AGE/VT United States Patent 3,212,171 METHOD OF MAKING COMMUTATORS William T. Echtcr, Rochester, N.Y., assignor to Echter Magnetic Products Company, Inc., Rochester, N.Y., a corporation of New York Filed Feb. 8, 1961, Ser. No. 87,818 2 Claims. (Cl. 29-15554) This invention relates to commutators and particularly to such commutators as are used on small electrical motors, generators or switches.

The use of commutators is, of course, well known and where commutators are used, it is frequently essential that a commutator be devised which can be easily manufactured at a very minimum of cost. Further, it is desirable that a commutator for such purposes eliminate the need for any assembly of the commutator elements per se. In motors or generators the brushes are usually arranged to contact the surface of the commutator which, in most instances, is a disc type divided into a number of sections or which can be a cylindrical type with axial slits to pro vide the necessary number of sections. In either case, each section is electrically connected to a winding of the motor or generator. Previously, such commutators were made by embedding sections or sectors in a soft insulating material or by securing the sectors to a disc of insulating material by riveting or otherwise fastening the sectors thereto. In each instance, the commutator sectors must first be made and then assembled with respect to the insulating material.

The present invention eliminates the need for assembling the disc and sectors and provides a commutator which is easily and inexpensively fabricated. This is accomplished by using an insulating material having a foil of electroconductive material bonded to one side thereof. The commutator disc is blanked or stamped from this material, with or without extending lugs. The disc is then divided into the necessary number of sections or sectors by compressing radial recesses in the disc on the side on which the electroconductive material is bonded. At the time the recesses are formed, the foil in the recesses must be disconnected or severed from the foil on the sectors so as to break any possible electrical connection. This is accomplished, in one instance, by compressing the insulating material sutficiently so the top surface of the foil in the recesses is below the surface of the sectors to which the foil is bonded. In this way, a commutator is provided which comprises a number of sectors all of the surfaces of which are coplanar so as to present a smooth surface for contacting or engaging the brushes. A commutator of the type described more completely hereinafter can be manufactured very inexpensively and does not necessitate any operation to remove the foil so as to disconnect the sectors electrically.

The primary object of the invention is, therefore, to simplify the structure of a commutator so as to render it easy to manufacture at a minimum cost and to eliminate any need for assembling parts to make such a commutator.

Another object of the invention is to provide a commutator of the type which presents a surface for engagement by the brushes of the motor or generator with which it is used wherein the surface of the sections or sectors of the commutator are coplanar and the sections or sectors are formed from the material comprising the commutator.

And yet another object :of the invention is to provide a commutator which can be made with a minimum number of operations from an insulating material having an electroconductive material bonded to one side thereof wherein the electroconductive material does not have to be removed in order to provide the necessary commutator sectors.

These and other objects and advantages will be apparent to those skilled in the art by the description which follows.

Reference is now made to the accompanying drawing wherein like numerals designate like parts and wherein:

FIG. 1 is a perspective view of a motor rotor and a commutator of my improved form mounted on the rotor shaft;

FIG. 2 is a plan view of a preferred embodiment of the commutator shown in FIG. 1;

FIG. 3 is a vertical sectional view taken substantially along line 33 of FIG. 2;

FIG. 4 is an enlarged vertical section taken substantially along the line 44 of FIG. 2;

FIGS. 5 and 6 are plan views of strips of the material from which the commutators are formed showing the steps to make a complete commutator;

FIG. 7 is a sectional view of a cylindrical commutator showing another manner in which axial slits can be formed to divide the commutator into a number of sections.

With reference to FIG. 1, the rotor 10 comprises an armature shaft 11 on which suitable cores 12 are mounted and provided with windings 13, as is well known in the art. A portion 14 of shaft 11 is knurled or serrated to receive the armature disc, designated broadly by the numeral 15, thereby preventing the disc from being rotatable on said shaft. As a matter of fact, the central aperture 16 of disc, 15 is slightly smaller in diameter than the diameter of shaft 11 so that disc 15 can be pressed onto the portion 14. It is to be understood, of course, that disc 15 can be mounted on or secured to shaft 11 in any other wellknown manner.

Disc 15 comprises an insulating material 17 and a foil 18 of electroconductive material such as silver, copper or any other suitable material, which is applied and/ or bonded to one side of material 17, see FIGS. 3 and 4, this sheet material being designated broadly by the numeral 25. Disc 15 is provided with three lugs 19 which extend radially from the periphery and which are equally spaced there about. A central annular recess 20 is formed concentric with aperture 16 and three recesses 21 extend radially from recess 20 to the periphery of disc 15, the recesses 21 being equally spaced centrally of lugs 19 to form three sections or sectors 22 each of which has a lug 19. When disc 15 is pressed onto the portion 14 of shaft 11, each of windings 13 is connected to one of lugs 19 in a wellknown manner, and, hence, to its respective commutator section or sector, as shown in FIG. 1. It is not essential that lugs 1? be equally spaced nor that windings 13 be connected to said lugs. If lugs 19 are not used, then the windings 13 canbe connected electrically to their respective section or sector in any well-known manner.

Since the foil 18 of electroconductive material is extensive over all of one surface of disc 15, the sectors 22 must be broken electrically if disc 15 is to function as a commutator. If the foil is removed, it can be done mechanically by peeling or scraping or chemically by anyone of several etching processes. Whether this is done ..mechanica1ly or electrically, several costly operations are required to prepare this disc for either of these operations. These operations can be completely eliminated by simply compressing the sheet material so as to break or displace the foil below the surface of the insulating material.

With reference to FIG. 4, the normal thickness of insulating material 17 and foil 18 of the electroconductive material is shown to the right side of aperture 16. It is to be understood, of course, that the relationships are not to scale, and hence, considerably exaggerated. The numeral 23 denotes the surface of 17 to which foil 18 is bonded. When material 17 is compressed, as shown to the left of aperture 16 and designated by 17, foil 18' remains of substantially the same thickness. However, to elimate any electrical contact between foil 18 on each of sectors 22 and foil 18' in the annular recess 20 and each of recesses 21, it is therefore necessary that the combined thickness of the compressed material 17' and foil 18 be less than the thickness of material 17 before it is compressed. In other words, the top surface of foil 18 as seen in FIG. 4, must be below surface 23 of material 17.

As shown in FIGS. 5 and 6, the commutator disc can be formed by first stamping or blanking three sectors 30 from material 25, each sector being separated from the adjoining sector by a bridge 31. At the same time, or by a separate operation, disc 15 can also be perforated with the central aperture 16. The central annular recess and the radial recesses 21 are then formed by compressing or striking disc 15 so as to sever foil 18 along the edges of the recesses and thereby displacing foil 18', the severed portions in recesses 20 and 21, below the surface 23 of insulating material 17. To obtain the disc 15 in its final form, bridges 31 are then severed along the dotted lines 32, as shown at the right in FIG. 5, thereby providing the lugs 19 which are shown in FIG. 2. As described hereinabove, annular recess 20 is concentric with aperture 16 and radial recesses 21 are arranged midway between the equally spaced bridges 31 so as to provide the three equal sectors 22. If lugs 19 are not required and windings 13 are connected directly to their respective section or sector, then as shown in FIG. 6, bridges 31 can be cut along the lines 33 in which case bridges 31 will remain within the opening 34.

Also, the operations necessary to provide disc 15 in its final and preferred form can be combined to perform a minimum number of operations and this, of course, will depend on the structure of the blanking tool, that is, whether it is designed so as to be a multipurpose tool which in a single cycle will perform each of the operations separately or some combination of the operations simultaneously.

In FIG. 7, another embodiment of the invention is shown in which the commutator 35 is cylindrical in form rather than a disc, as described above. The insulating material 36 is tubular in form and has an electroconductive material 37 applied or bonded to its exterior surface. Three longitudinal sections 38 are formed by striking the cylinder along each of three axial lines to break the material 37, thereby forming three axial recesses 39 and isolating each section 38 electrically. This can be accomplished by using a tool which strikes and severs the material 37 and compresses it into the insulating material 36. Recesses 39 can be formed separately; that is, by three separate operations, or by a single operation in which the three recesses 39 are formed simultaneously.

While foil 18 is described above as being below the surfac: 23 of material 17, the recesses 21 can be of the form shown in FIG. 7; that is, the same as recesses 39. Likewise, the recesses 39 can be of the type shown in FIGS. 3 and 4. The primary requisite is that the electroconductive material be broken or displaced sufficiently so as to eliminate any electrical connection between two adjacent sections or sectors of the commutator.

There are any number of materials with an electroconductive layer or foil applied and/or bonded thereto which will be suitable for a commutator of the type described hereinabove. Also, the size of the commutator need not be limited to those which are used in conjunction with very small motors. It will be readily apparent to those skilled in the art that many modifications can be made in the commutator described hereinabove; however, the invention is not to be limited to the embodiments described and disclosed but is of a scope as defined by the appended claims.

Having now particularly described my invention, what I desire to secure by Letters Patent of the United States and what I claim is:

1. A method of making a disc commutator having extending lugs from a flat sheet of fully cured insulating material having a foil of electroconductive material bonded to one surface thereof which comprises:

cutting a plurality of equiangular circular annuli from said sheet, each annulus having the same inner radius and the same outer radius and being separated from the adjacent annuli by a bridge of said sheet;

perforating an aperture centrally with respect to said annuli in said sheet;

forcing a relatively narrow area of said electroconductive material disposed between each pair of adjacent bridges and extending radially from said aperture to the inner radius of its respective annulus into said insulating material to a sufiicient depth below said one surface of the latter to effect an electrical disconnection of each of said areas from the rest of said electroconductive material; and

cutting said bridges at the outer radius of said annuli.

2. The method of making a disc commutator having extending lugs from a fiat sheet of fully cured insulating material having a foil of electroconductive material bonded to one surface thereof which comprises:

simultaneously cutting three equiangular, circular annuli from said sheet, each annulus having the same inner radius and the same outer radius and being separated from adjacent annuli by a bridge of said sheet;

perforating an aperture centnally with respect to said annuli in said sheet;

forcing an area of said electroconductive material into said insulating material to a sufiicient depth below said one surface of the latter so as to effect an electrical disconnection of said area from the rest of said electroconductive material, said area comprising an annular area surrounding said aperture and a relatively narrow area disposed equiangularly between each pair of adjacent bridges and extending radially from said annular area to the inner radius of its respective annulus; and

cutting said bridges at the outer radius of said annuli.

References Cited by the Examiner UNITED STATES PATENTS 489,000 1/93 Groswith et al 310-237 1,432,038 10/22 Russell 29-l55.54 1,499,622 7/24 Markwalder 310237 2,963,774 12/60 Pike 29155.54 2,988,839 6/61 Greenman et al 294155.54

3,010,182 11/61 Ouinlan 29155.54 3,059,323 10/62 Moressee 29155.54

WHITMORE A. WILTZ, Primary Examiner.

MILTON O. HIRSHFIELD, JOHN F. CAMPBELL,

Examiners. 

1. A METHOD OF MAKING WOUND CAPACITORS WITH TWO TENDING LUGS FROM A FLAT SHEET OF FULLY CURED INSULATING MATERIAL HAVING A FOIL OF ELECTROCONDUCTIVE MATERIAL BONDED TO ONE SURFACE THEREOF WHICH COMPRISES: CUTTING A PLURALITY OF EQUIANGULAR CIRCULAR ANNULI FROM SAID SHEET, EACH ANNULUS HAVING THE SAME INNER RADIUS AND THE SAME OUTER RADIUS AND BEING SEPARATED FROM THE ADJACENT ANNULI BY A BRIDGE OF SAID SHEET; PERFORATING AN APERTURE CENTRALLY WITH RESPECT TO SAID ANNULI IN SAID SHEET; FORCING A RELATIVELY NARROW AREA OF SAID ELECTROCONDUCTIVE MATERIAL DISPOSED BETWEEN EACH PAIR OF ADJACENT BRIDGES AND EXTENDING RADIALLY FROM SAID APERTURE TO THE INNER RADIUS OF ITS RESPECTIVE ANNULUS INTO SAID INSULATING MATERIAL TO A SUFFICIENT DEPTH BELOW SAID ONE SURFACE OF THE LATTER TO EFFECT AN ELECTRICAL DISCONNECTION OF EACH OF SAID AREAS FROM THE REST OF SAID ELECTROCONDUCTIVE MATERIAL; AND CUTTING SAID BRIDGES AT THE OUTER RADIUS OF SAID ANNULI. 